Federation of user identity provides a mechanism for a remote provider to authenticate users across multiple computer systems. A number of standards, such as Security Assertion Markup Language (SAML), OpenID Connect, Web Services (WS)-Federation, provide consistent interfaces to convey the federated user identity across the multiple computer systems. One use of a federated user identity allows an authenticated user access to Software-as-a-Service (SaaS) in which an application is remotely hosted and maintained for the authenticated user.